The present invention is directed to lugs for establishing electrical continuity between a cable and an electrical distribution device. More particularly, the present invention is directed to a lay-in lug having a configuration which may be used for in so-called main lug or main breaker load center applications.
Load centers and similar electrical devices have bus bars which are connected to electrical power source cables. The bus bars are often connected to the power supply cables by a lug which captures an electrically conductive portion of the cable in a biased contact. Two common lug configurations are solid lugs, which have a bore into which a cable end is inserted. The cable is fixedly retained in the lug bore by a threaded allen head bolt. Another type of known lug is a so-called lay-in lug which has a two piece structure with each piece defining a slot. The cable is laid in the slot of a first portion of the lug. The second portion of the lug is attached to the first portion so that the cable is clamped between the two portions.
Both types of the above-described lugs have been used in main lug and main breaker-type load centers. In main lug load centers, the power cables are connected directly to conductive main or load bus bars, whereas in main breaker load centers, a circuit breaker is interposed between the cables and the load bus bars for circuit protection. In the past, each of the main lug and main breaker-type load centers required different lug designs or some type of adapter strap had to be fabricated to connect the lug to the main breaker line contacts.
U.S. Pat. No. 4,536,823, shows a connectable solid-type lug 22 or 24, which may be utilized in either main breaker or main lug load center applications. The lug 22 or 24 has lug base ledges 70, 72 which are captured in a channel 64 in load center base 14. The lug 22, 24 has a pair of upstanding ribs 122, 124 which are engageable in the line end contacts of a main breaker. A drawback in main lug applications is that the upstanding ribs 122, 124 add unnecessary length to the load center structure.
The lug shown in U.S. Pat. No. 4,536,823 is a cast structure which is relatively expensive to manufacture. It is desirable to utilize less expensive manufacturing processes, such as extrusion or stamping processes.
Another known way to utilize a single lug in both main lug and main breaker applications is to have a separate U-shaped structure with upstanding ribs attached to the lug, so that upstanding ribs can be inserted into main breaker line contacts. In one known example, the U structure has a finger or tongue, which is interposed in a bore in the lug between the cable and a rectangular extension similar to the one shown in the lug 22 in the lug of U.S. Pat. No. 4,536,823. A drawback to this solution is the need to inventory the additional U-shaped component in the manufacturing facility.
It is an object of the present invention to create a lay-in lug that can be extruded.
It is another object of the present invention to create a lug configuration that can be used in main breaker or main lug load centers, so as to eliminate the need for separate lug designs.
It is an object of the present invention to create a single lug configuration that can be utilized in main lug or main breaker load centers without the need for auxiliary brackets or adapters.
It is an object of the present invention to create a lay-in lug configuration that can be utilized in main lug or main breaker load centers, but that does not have excessive length in main lug applications.